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<br />
<br />(G. W.Leavesley, oral commun~, 1975), These results will be integrated into
<br />both the flow-routing and reservoir-assessment elements.
<br />
<br />Minimwrz-fZow anaZyais.--A low-flow analysis will be made for the basin
<br />using the Log-Pearson Type III frequency analysis. Low-flow characteristics
<br />will be computed for 7-, 10-, and 30-day minimum mean flow periods at 2-, 10-,
<br />and 20-year recurrence intervals. As noted by Livingston (1970) and Wah'l
<br />(1970), minimum-flow analysis in Colorado and Wyoming is quite complicated
<br />because of surfa'ce-water diversions, topography, geography, and cl imate, In
<br />the Yampa-River basin, diversion of water is quite prevalent, affecting ma'ny
<br />daily streamflow records.
<br />
<br />For the minimum-flow analysis, the water-d"lvers ion data, described ear-
<br />lier, will be.used with the existing surface-water records to reconstruct
<br />estimated natural flows at the various surface-water sites, These data then
<br />will be used in the minimum-flow analysis.. D. R. Tuthill, Jr;,while a grad-
<br />uate student in civil engineering at the University of Colorado, assisted the
<br />project staff In this assessment-analysis component, and his findings are pre-
<br />sented in his masterts thesis (Tuthill, 1975),
<br />
<br />Time-of~tT'aveZ studies,--One or two time-of-travel studies are planned
<br />for the Yampa River mainstem from, Steamboat Springs to Craig, Colo., and the
<br />Little Snake River malnstem from Slater to Baggs, Wyo, The time-of-travel
<br />studies will be made during the spring high-flow and summer low..,flow periods
<br />of 1976. Field measurements will be made at these two different discharge
<br />conditions and an approximate time-of-travel versus discharge relationship
<br />wi 11 be developed for the study reach (Bauer, 1968), These studies wi 11 en-
<br />able a moreeritical analysis to be made on hydraul ic-flow conditions as a
<br />basis for evaluating the waste-assimilative capacity of the upper'Vampa River
<br />mainstem.
<br />
<br />The time-of-.travel studies will be made by the dye-tracer technique
<br />'(Wilson, 1968).'"The dye "cloud" will be analyzed for longitudinal dispersion
<br />and peak concen.trationdecay.
<br />
<br />GroundWater
<br />
<br />The primary use of ground water in ,the Yampa River 'basin has been for do..;
<br />'mestic, livestock, and municipal ,suppl ies.Wells princi.pally have been dri 11-
<br />-edln unconfined ,alluvial aquf'fers that generally followst'ream-cut valleys.
<br />""Mostwells:are'less than 100 feet OOm) deep, but a few have penetrated:deep-
<br />, e-r iaqu lfers.
<br />
<br />Results cif .two ongoing ground-water reconnaissance investigations by the
<br />U.S. .:Geological'Survey in cooperation with the Colorado Division of Water Re-
<br />"sources, Office:of ,the State Engineer, and the U,S. Environmental Protection
<br />Agency will p'rovi.de supplemental information, A few of the inventoried wells
<br />may be designated:as monitoring sites for periodic observations of water lev-
<br />els :and selected water-qual itymeasurements, In addition, several deep wells
<br />presently arebei'ng drilled in ,.the northeastern part of t.he basin in Wyoming
<br />as part ofa Hthological study by ,the Geological Survey, Once completed,
<br />some .of these wells .will :bemaJntaine.das observation wells for water levels.
<br />
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